Notes | null v undefined

null v undefined

	null	undefined
means	Assigned value, means nothing needs explicit assignment	Variable declared, but not defined. Variable's default value.
typeof	object	undefined

var a; //undefined
var b = null; //null

null = 'value' //Reference error
undefined = 'value' //value

null == undefined  //true

null === undefined  //false
null == 0  //false

var undefined = null;
undefined === null //true

undefined is the only value that can't get explicitly passed in for a default-value parameter

function foo(a = 2) {
  console.log(a);
}

foo(null);	// null
foo(undefined);	// 2